[Elecraft] K3 pwr out on digimodes

[Julian, G4ILO]

hb9ari wrote:
> 
> Benson,
> 
> I've done some measurements some time ago with my K3 #1212 and i had the 
> following values:
> K3 power set to 20W, f=7.040MHz   25W 50 Ohms dummy load 
> MCE/Weinschel    LP-100A Wattmeter
> mode USB   1 kHz sine audio at rear line-input, level adjusted to have 
> the desired ALC bar configuration
> 
> ALC bar(s)           Mesured [W] (avg)
> 0                             8.16
> 1 blinking                  9.4
> 1steady+1blk         15.95
> 2steady+1blk         20.72
> 3steady+1blk         21.2
> 
> These values correspond to the above mentioned set-up (K3 #1212 uP rev 
> 2.78) and displayed on the LP-100A with RF head #1143
> 
> 73 QRO fr Rudolf, HB9ARI
> 
> 

I would be quite happy if my K3 consistently gave results such as you
tabulated.

I was going to produce a similar table to illustrate the problem I am
experiencing, only with PWR set to 2.0W rather than 20W. I switched on the
radio and observed that I was getting more than 5.0W, with 5 blocks showing
on the K3 internal meter. This did not start to reduce until MIC was turned
down until no ALC bars were showing.

I made a false start in creating the table as I found that the MIC control
was too coarse to show all the levels of ALC you tabulated, so I started
again using the computer sound card level slider to regulate the input
level. At this point I found that the power was now being limited to about
3.0W, with just two blocks showing on the K3 power meter.

This is the behaviour which is driving me crazy. There is no setting of the
MIC and PWR controls that consistently delivers a given power in DATA A
mode. You never know how much power the rig is going to put out the first
time you click the TX button after you have switched on, changed band or
changed frequency.

Once it decides to regulate the power, it does seem to remain fairly
consistent as long as you stay on that band and that frequency.

The problem with controlling the power using the audio input level instead
of setting it to 4 "ALC bars" as Lyle originally advised is that the power
output becomes frequency dependent. I can vary the output power between 5.0W
and 10.0W just by clicking in a different place on the waterfall, varying
the frequency of the audio input. The power at 500Hz or 2000Hz is about half
what it is at 1200Hz. It is hopeless for anyone who wants to operate using
Digipan "click and call" style operating.

-----
Julian, G4ILO. K2 #392  K3 #222.
http://www.g4ilo.com/ G4ILO's Shack   http://www.ham-directory.com/ Ham
Directory    http://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 
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